It’s got to be out there. It doesn’t matter that Otodus megalodon has by all scientific accounts been extinct for more than 3 million years. The ongoing earthly presence of the enormous shark persists in our collective imagination thanks to rumors, legends, and summer B flicks.
Meg mythology often posits that the 50-foot predator has been hiding for epochs somewhere at the bottom of the ocean. It’s a notion that’s launched more than a few books and pseudo-docs, all hinging on the fact that most of the planet’s nether waters are unexplored—and therefore rife with primo dens for enigmatic beasts. But based on what we know of the biological adaptations required for life down below, not many animals could pull off a deep-sea disappearing act. If megalodon is still out there (and that’s a pretty big if), it’s not what it used to be.
Fossil shark teeth got people hooked on the Meg long before paleontology took off in the early 19th century, when scientists started cataloging fossils with gusto. In 1835, Swiss naturalist Louis Agassiz described triangular, finely serrated teeth, which had been found worldwide since antiquity, as belonging to a “megatooth” relative of the great white.
Discoveries around the world—in locations as diverse as Panama, Japan, Australia, and the southeastern United States—piled up over time, but one particular find raised the specter of a Meg still swimming in the deep. In 1875, during an expedition for the Royal Society of London, the HMS Challenger dredged up 4-inch-long teeth from a depth of 14,000 feet near Tahiti. In 1959, zoologist Wladimir Tschernezky, who made a hobby of researching “hidden animals” like Bigfoot, estimated the specimens were just 11,300 years old. Other scientists have since dismissed this dating, but unscrupulous documentarians and curious amateurs still highlight the research as a hint that Meg might persist.

For decades Otodus megalodon has been depicted as an oversize great white. But thanks to new analyses of where it sits on the shark family tree, the predator scientists know now is very different from the Jaws star.Esther van Hulsen
A history of the megalodon
16 million years ago - Otodus megalodon evolves from an ancestral group of megatooth sharks—the last member of a line that began 60 million years ago.

10 million years ago - The shark spreads to coastal waters worldwide. Clusters of baby teeth near Panama suggest nurseries were close to shore.

5 million years ago - Great white sharks evolve, and likely compete with the massive Meg to eat the same marine mammals, such as whales.

3.5 million years ago - Otodus megalodon seemingly goes extinct around a time of upheaval, including cooling seas and a dip in the species it munched on.

70 CE - Pliny the Elder notes that large “tongue stones” found in the rock strata of Europe may fall from the heavens during lunar eclipses.

1666 - Danish scientist Nicolas Steno dissects the head of a shark found off the coast of Italy and speculates that “tongue stones” are teeth.

1835 - Swiss naturalist Louis Agassiz coins the name Carcharodon megalodon in describing a set of the creature’s giant chompers.
1875 - The HMS Challenger dredges up megalodon teeth from the deep sea near Tahiti, fueling speculation about the shark’s survival.

1909 - Researchers build a model of a Meg jaw that fits six standing adults—suggesting an 80-foot body. This is now considered oversize.

1919 - Fishers in Australia claim to see a massive shark eat multiple lobster pots. The legend eventually makes its way into megalodon lore.

1974 - Peter Benchley publishes Jaws, which plays with the idea that a prehistoric man-eater might lurk in the deep. The public is hooked.

2016 - After decades of debate on the specifics of Meg’s family tree, the giant shark gets the new scientific name Otodus megalodon.

This story appears in the Fall 2020, Mysteries issue of Popular Science.